From: Daniel Schierbeck <daniel.schierbeck@...>
Date: 2006-06-20T02:03:22+09:00
Subject: Re: Is it more convenient to have a random_each in ruby stdlib?

Matthew Smillie wrote:
> Anyway, Array's just a special case: I'd say that it belongs in 
> Enumerable along with sort, for which I'd grab your implementation.
> 
> module Enumerable
>   def shuffle
>     entries.values_at(*(0...entries.size).entries.shuffle!)
>   end
> end

Yup, Enumerable's the place it should be.


> Though this still relies on Array#shuffle!, which I can't say is a good 
> or bad thing.

Since #shuffle! would alter the receiver, it shouldn't be defined in 
Enumerable. Other ordered collections could implement their own versions.

I was wondering, is Ruby's internal variable "switching" faster than 
using a temperary variable? #shuffle! can be written like this, but I 
don't know if it's faster.

   def shuffle!
     each_index do |i|
       r = rand(size - i) + i
       self[i], self[r] = self[r], self[i]
     end
   end


Cheers,
Daniel